Re: Good mother dinos

[NEIL CLARK <NCLARK@museum.gla.ac.uk>]

> From:          Tracy Monaghan <monaghan@cac.washington.edu>

> 1) How easy is it to distinguished eggshells pulverized by 
hatchlings from 
> shells pulverized by a gazillion years of sediments?

One method that I have used, in conjunction with eggshell experts at 
the Vet School in Glasgow, is to look at the crystalline ultrastructure of 
the eggshell.  Although this is more circumstantial, and I only use it to 
distinguish between hatched and unhatched eggs, the eggshell of 
hatched eggs is substantially depleted in calcite (gaps in the 
crystallite structure of the shell) due to it being absorbed by the 
growing embryo to help in the calcification of bone.  The only problem 
with this is that diagenetic fluids can produce the same effect, so the 
sheel has to be looked at in context.  Whethter or not the crushing of 
the shell is due to the hatchling or to other animals may be difficult to 
say, but it should be relatively easy to distinguish between sediment 
compaction crushing and biogenic crushing.
> 
> 2) Have dino-nests been found which contained shells more-or-less 
intact?
> 
Yes, I have a clutch of eggs with complete and intact eggs.  Some of 
the eggs may contain embryos.  In fact I know of at least 15 eggs in 
which the embryo is still inside the egg and is also complete 
(although slightly disarticulated).  The only problem is that I cannot 
get to study them as they cost in excess of 2.5million dollars US. 


Neil Clark
Curator of Palaeontology
Hunterian Museum
University of Glasgow
email: NCLARK@museum.gla.ac.uk

The first law of Geology is the law of supposition.
(Geological Howlers - ed. WDI Rolfe)